Ｎｉ，Ｃｕ基板に対するＣのＭｅＶ注入による表面硬化のメカニズム

Abstract

It has been confirmed that differences in solid solubility is important in surface hardening by MeV ion implantation.Using two substrates-Ni and Cu-which exhibit a similar crystal structure (f.c.c) and interatomic distances, the structural transformation due to MeV ion implantation was analyzed. Since carbon has slight solid solubility to Ni but not to Cu, 3MeV carbon implantation of the substrates was carried out at doses of 1×1016-5×1017ions/cm2.The hardness depth profile in the implant layer was estimated by a dynamic micro hardness tester. Microstructure produced by implantation was obserbed by microscope. The crystal structures were investigated by XRD. AES and SIMS were also performed to obtain the profile of the implantated carbon.Remarkable differences between Ni and Cu are found in terms of hardness profiles, implantation ion distribution, and crystal structure transformation. With Ni, maxium hardness with Gaussian profile occurred at a dose of 3×1016ions/cm2, and it is considered that internal stress is the major facter in hardening up to this dose range. At doses above 1×1017ions/cm2, recrystalization may cause a broadening of the hardening profile, and the production of carbide compounds is thought to be the cause of the hardening. In the case of Cu, the hardness distribution becomes scattered with increases in dose. It is thought that this is due to the fact that the implanted carbon gradually precipitated because carbon has no solid solubility in Cu.